Schizophrenia is a severe mental disorder that affects how a person thinks, feels, and behaves. It is associated with subtle abnormalities in day-to-day social behaviors and one of the leading causes of disability in the United States. Unfortunately, little is known about the abnormalities in real-world social functioning in individuals with schizophrenia, how their abnormalities correlate with clinical symptoms and progress over time as a consequence of therapeutic interventions. The real-world assessment of personal space - the physical distance that one maintains from others during social interactions - can be used to develop and efficiently evaluate potential treatments for schizophrenia and help improve patients' day-to- day functioning. The goal of this study is to objectively quantify the amount of real-world social interactions and the physical distance maintained from others in individuals with schizophrenia. Specific research aims include: 1) Design and implement a neck-worn device that employs acoustic signals to detect human targets that the patient interacts with. 2) Design a method to simultaneously measure the distance between the patient and multiple targets at an accuracy level of 2 cm with ultrasound. 3) Explore the unique markers of social functioning in healthy individuals and patients with schizophrenia by integrating the personal space information and other multi-dimensional contextual and behavioral information, and 4) Develop an algorithm that extracts relevant features from the obtained data that can be used to assess the level of social motivation and the severity of symptoms in schizophrenia patients. We believe that progress towards moving schizophrenia treatment to a scientific process rooted in objective measurement and performance in the real-world would contribute to a major paradigm shift in the field. More specifically, the outcomes of the proposed research - if successful - will transform the understanding and treatment of schizophrenia, opening a new door leading to previously unexplored datasets and potentially new development of personalized disease management, which well-aligns with the mission of the National Institute of Mental Health. RELEVANCE (See Instructions): The real-world assessment of personal space can be used to develop and evaluate potential treatments for schizophrenia and help improve patients' day-to-day functioning. The goal of this study is to objectively quantify the amount of real-world social interactions and the physical distance maintained from others in individuals with schizophrenia. The proposed study will open a new door leading to previously unexplored datasets and new development of personalized disease management in schizophrenia.